SAN FRANCISCO, April 7, 2013 /PRNewswire/ -- Nektar Therapeutics (Nasdaq: NKTR) today presented positive preclinical data for NKTR-214, a novel cancer immunotherapy which targets the IL-2 receptor complex, at the 2013 American Association for Cancer Research (AACR) Annual Meeting. NKTR-214 is a new immunocytokine that is being developed as a potential treatment for multiple cancers. NKTR-214 targets the IL-2 receptor complex through selective receptor binding to the IL2Rβ subtype. Activation of the IL2Rβ subtype promotes tumor killing by the body's own immune system.

"We are extremely encouraged by the dramatic efficacy observed with NKTR-214 treatment in an aggressive and resistant preclinical model of melanoma," said Stephen Doberstein, Ph.D., Senior Vice President and Chief Scientific Officer of Nektar Therapeutics. "NKTR-214 is specifically designed to harness the potent immunostimulatory effects of the IL-2 receptor complex while minimizing the immunosuppressive effects that have greatly limited the efficacy of the native IL-2 protein. Importantly, NKTR-214 represents the first application of our technology platform to target a receptor subtype in the tumor microenvironment while avoiding the unwanted effects from off-target receptor binding. NKTR-214 also has improved pharmacokinetics and enhanced tumor penetration which allow for a ten-fold reduction in overall dosing. We are excited about the potential of NKTR-214 to emerge as a powerful new immunotherapy in the fight against cancer."

NKTR-214 is a novel immunocytokine therapy that is engineered using Nektar's polymer conjugate technology to selectively target the beneficial IL-2 receptor complex. In the preclinical data presented at AACR, NKTR-214 exhibits differentiated IL-2 receptor binding which results in significantly altered immune cell populations in the tumor microenvironment compared to the clinically validated IL-2 protein therapy, aldesleukin. Specifically, NKTR-214 maintains high affinity for the IL-2 receptor subunit beta, which activates tumor-killing T cells within the tumor microenvironment. At the same time, NKTR-214 exhibits up to 100-fold reduced affinity to the IL-2 receptor subunit alpha-beta, which activates immuno-suppressive regulatory T-cells. In a well-validated animal model of melanoma, NKTR-214 demonstrated significantly improved dosing, at once every 9 days as compared to twice a day dosing with aldesleukin.

About Nektar Nektar Therapeutics is a biopharmaceutical company developing novel therapeutics based on its PEGylation and advanced polymer conjugation technology platforms. Nektar has a robust R&D pipeline of potentially high-value therapeutics in pain, oncology and other therapeutic areas. In the area of pain, Nektar has an exclusive worldwide license agreement with AstraZeneca for naloxegol (NKTR-118), an investigational drug candidate, which has completed Phase 3 clinical development as a once- daily, oral tablet for the treatment of opioid-induced constipation. This agreement also includes NKTR-119, an earlier stage development program that is a co-formulation of naloxegol and an opioid. In the proprietary pipeline, NKTR-181, a novel mu-opioid analgesic candidate for chronic pain conditions, is in Phase 2 development in osteoarthritis patients with chronic knee pain. NKTR-192, a novel mu-opioid analgesic in development to treat acute pain is in Phase 1 clinical development. In oncology, etirinotecan pegol (NKTR-102) is being evaluated in a Phase 3 clinical study (the BEACON study) for the treatment of metastatic breast cancer and is also in Phase 2 studies for the treatment of ovarian and colorectal cancers.

Nektar's technology has enabled eight approved products in the U.S. or Europe through partnerships with leading biopharmaceutical companies, including UCB's Cimzia® for Crohn's disease and rheumatoid arthritis, Roche's PEGASYS® for hepatitis C and Amgen's Neulasta® for neutropenia. Additional development-stage products that leverage Nektar's proprietary technology platform include Baxter's BAX 855, a long-acting PEGylated rFVIII program, which is in Phase 3 clinical development.

Nektar is headquartered in San Francisco, California, with additional operations in Huntsville, Alabama and Hyderabad, India. Further information about the company and its drug development programs and capabilities may be found online at http://www.nektar.com.

Cautionary Note Regarding Forward-Looking Statements This press release contains "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements can be identified by words such as: "anticipate," "intend," "plan," "expect," "believe," "should," "may," "will" and similar references to future periods. Examples of forward-looking statements include, among others, statements we make regarding the therapeutic potential of NKTR-214 and the value and potential of our technology and drug candidates in our research and development pipeline. Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based only on our current beliefs, expectations and assumptions regarding the future of our business, future plans and strategies, anticipated events and trends, the economy and other future conditions. Because forward-looking statements relate to the future, they are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict and many of which are outside of our control. Our actual results may differ materially from those indicated in the forward-looking statements. Therefore, you should not rely on any of these forward-looking statements. Important factors that could cause our actual results to differ materially from those indicated in the forward-looking statements include, among others, (i) positive preclinical efficacy findings, such as those for NKTR-214 reported in this press release, are subject to inherent scientific and medical uncertainties typical for this stage of drug development and may not be confirmed in subsequent preclinical studies or in clinical trials; (ii) NKTR-214 is in early stage research and there are a number of hurdles, including the successful completion of preclinical toxicology studies, prior to NKTR-214 being ready to enter into clinical development; (iii) our drug candidates and those of our collaboration partners are in various stages of clinical development and the risk of failure is high and can unexpectedly occur at any stage prior to regulatory approval for numerous reasons including safety and efficacy findings even after positive findings in previous preclinical and clinical studies; (iv) the timing of the commencement or end of clinical trials and the commercial launch of our drug candidates may be delayed or unsuccessful due to regulatory delays, slower than anticipated patient enrollment, manufacturing challenges, changing standards of care, evolving regulatory requirements, clinical trial design, clinical outcomes, competitive factors, or delay or failure in ultimately obtaining regulatory approval in one or more important markets; (v) acceptance, review and approval decisions for new drug applications by health authorities is an uncertain and evolving process and health authorities retain significant discretion at all stages of the regulatory review and approval decision process; (vi) scientific discovery of new medical breakthroughs is an inherently uncertain process and the future success of the application of our technology platform to potential new drug candidates is therefore highly uncertain and unpredictable and one or more research and development programs could fail; and (vii) certain other important risks and uncertainties set forth in our Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 1, 2013. Any forward-looking statement made by us in this press release is based only on information currently available to us and speaks only as of the date on which it is made. We undertake no obligation to update any forward-looking statement, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or otherwise.